早期电视机的视频检波均采用大信号包络检波电路，后来在集成化的电视机中，视频检波又都采用同步检波方式。

All circuits of demodulating strong signal envelope are adopted in previous TV's video demodulation, synchronizing demodulations are widely used in video demodulation in the later integrated TV set.

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由准同步视频检波的特点及其存在的问题引出锁相环（ PLL）完全同步视频检波电路。

The PLL full synchronization video detector circuit is educed by feature and troubles of quasi-synchronization video detector.

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